The long-term goal of this project is to create commercially available probes which greatly enhance the sensitivity of NMR (nuclear magnetic resonance) spectrometers. These probes will utilize thin-film receive coils of YBCO (Y1Ba2Cu3O7), a high-temperature superconductor (HTS). The YBCO coil is expected to provide an improvement in signal-to-noise ratio (SNR) of a factor of 10 for nonconductive samples and 3 for physiological samples. A working prototype 400-MHz 1H probe has already been created. This probe contains a YBCO coil which has an unloaded quality factor (Qu) at 20 K in the 9.4-T magnet greater than 10,000, more than 50 times that of normal-metal coils. It is cooled by open-cycle flowing liquid helium. The proposed project will create a continuously operating, closed-cycle, user-friendly probe containing similar coils, including a 2H lock, coupled to a cold preamplifier. The end goal is a probe with a 5-fold improvement in SNR over conventional probes (for nonconductive samples), with lineshape as narrow as that of conventional probes, and with 90-day maintenance-free operation. PROPOSED COMMERCIAL APPLICATION: An NMR spectroscopy probe using high- temperature superconductors would extend the chemical sensitivity of existing and new machines by a factor of ten. NMR spectrometers represent a $190 M per year industry. The commercial market for a user-friendly probe is estimated at $10,000,000 to $20,000,000 per year.